[dredmorbius]

"Radiation" here refers to thermal radiation --- the direct radiant heat released through atmospheric friction and blast.

The shockwave itself is also radiant energy, in this case a kinetic overpressure wave.

Net impact effects are "wind blast, overpressure shock, thermal radiation, cratering, seismic shaking, ejecta deposition, and tsunami":

<https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/201...>

Remember that "radiation" simply refers to any effect that radiates outward from an initial point or source, say, a radiator. Yes, common parlance has abbreviated "ionizing nuclear radiation" as "radiation", but that's only one of numerous types of radiant energy.

[midoridensha]

When someone says "a nuclear bomb releases heat and radiation", the radiation they're referring to is not thermal radiation. You're being pedantic.

[dredmorbius]

The link I provided gives alternate usage. You might wish to reconsider your position.